1. Field of the Invention
The present invention relates to a printing system comprising a host device and a printer connected through a network.
2. Description of the Related Art
As computing devices are increasingly being networked, printing systems of this type have become increasingly common. In many cases, multiple host devices and multiple printers are linked to the same network. When a host device has data to be printed, it selects one of the connected printers and sends the data to the selected printer. First, however, the host device may also need to set the printer up by selecting a particular printing mode, such as a particular printing density, possibly changing settings that have been made previously by the same or another host device. The new settings are stored in a memory in the printer.
The information set by a host device in a printer is not limited to printing mode settings. For example, Internet Protocol (IP) addresses are often used to facilitate access to networked printers, but most printers lack a control panel from which an IP address can be entered, so the IP address must be sent to the printer from a host device.
A conventional procedure used for selecting a printer and setting it up starts by having a host device broadcast a query on the network, asking for replies from devices that can accept printer setting information. Typically, the host device receives replies from all printers connected to the network, and does not receive replies from other types of devices. The operator of the host device sees a list of printers, identified by their network addresses, displayed on a screen, and selects one printer from the list. The host device then sends the necessary printer setting information to the selected printer.
A problem is that the network addresses seen by the operator generally give few clues as to the location or identity of the printers. For example, the network addresses may be IP addresses or Ethernet media access control addresses, which are strings of digits, and an address may identify, not the printer itself, but a network interface card installed in the printer. Considerable time and effort may be required to determine which address belongs to which printer in the network, and the operator can easily make a mistake, causing the host device to try to set up the wrong printer. The problem can be alleviated to some extent by translating a printer's IP address into a more easily recognizable name, but network addresses of the readily mistakable type must still be used when, for example, a printer is first connected to the network and has not yet been given either an easily recognizable name or an IP address. (Ethernet is a registered trademark.)
A further problem is that the conventional procedure generates unnecessary network traffic in the form of, for example, responses from printers that do not need to be set up.
Japanese Unexamined Patent Application Publication No. 11-249989 proposes a scheme in which, after sending the initial query and receiving responses, the host device sends the selected printer the well-known Ping command to determine whether it has an IP address, and uses the IP address, if it has been correctly set, to make further settings. This scheme provides a way to confirm that the intended printer has been selected, but the Ping command generates additional network traffic and creates further delays in the setting procedure, because the host device has to wait for a response to the Ping command.
If there is a delay between the response to the initial query and the sending of the printer setting information, yet another problem may occur: during the delay, a different host device may attempt to set up the same printer.
A more general problem is that when host devices and printers are interconnected by a network there is always the possibility that the settings of a printer may be tampered with, inadvertently or otherwise, by a host device that should not alter the settings of that particular printer.